newsletter

Why is the moon round?

The Moon, like the Sun, the Earth and the other planets, is a big round object in space. Sometimes it might not look round. It might look like a semicircle or a crescent in the sky, but that’s just because the Earth’s shadow covers part of it. When there’s a full moon, we see the Moon’s full shape, a sphere.

The moon got its shape because of gravity. It has gravity just like the Earth does. Gravity pulls everything to the center of a big object. That’s why we don’t float off into space. The Earth is pulling us to its center!

The Moon may have started out as a weird and irregular shape or as a bunch of floating chunks of rocks, but over time, gravity collected it, pulling and tugging the rocks that make up the Moon together until they were collected into a neat, round ball.

Exploration

Gripping Gravity!

Gravity likes to follow very strict rules. Besides pulling planets, moons and stars into nice, even, round shapes, it also pulls things at the exact same speed. You can check this out for yourself at home.

If you hold a basketball and a tennis ball from the same height and drop them at the same time, which one will hit the ground first? Ask a grown-up to do the dropping so you can watch.

Why do they fall the way they do? Gravity is very consistent and it doesn’t really care how heavy an object is. It pulls everything the same way! Sometimes though wind and air can get in the way of gravity’s pull. They can affect the speed that things fall, so a piece of paper might take longer to reach the ground than the basketball.